Light emitting diode (LED) modules, such as in the form of a spot module, is one of many lighting device types which are available today. LED modules typically comprises a light source device, such as one or more LED packages, a chip on board (COB) module or a printed circuit board (PCB) with discrete LED packages, and a cover for the light source device. The cover is provided for e.g. protecting the light source device, providing a mechanical reference surface, and/or connection of a reflector thereto.
The light source device may further comprise a phosphor element, in some cases remotely arranged, for modifying the light provided by the LEDs. For example, white light may be achieved by LEDs providing blue light which passes through a phosphor element, where some of the light is converted into yellow light. Thus, the output light comprising blue and yellow components gives an overall white impression. The phosphor element is typically provided on top of the LED part of the light source device. In some configurations, the phosphor element may instead be provided as a phosphor disk arranged at a distance from the LED part of the light source device.
The cover is typically made of a plastic material with a relatively low thermal conductivity and not suitable to be used as heat conductor, and adapted to be arranged over the light source device but still let through the light provided by the light source(s). The cover may e.g. comprise a centered aperture to be arranged over the light source(s) of the light source device.
An optical device, such as a reflector, a collimator or a lens, is typically connected to the LED module for providing e.g. focusing of the provided light in a specific direction. A reflector base of a reflector may for example be arranged in a recessed area of the cover.
The light source device generates heat, both from the LED part and the phosphor element (if included). It is desirable to remove as much of the generated heat as possible in order to not overheat the LED module. For the LED part of the light source device, overheating may result in a lower efficacy and a reduced lifetime of the LEDs. For the phosphor element, overheating may result in quenching effect leading to poor light conversion efficiency. In order to lead away heat, LED modules are connected to a heat sink which is mounted to a backside of the LED module. The heat sink is arranged adjacent to a part of the light source device, such that heat generated by the light source device is dissipated via the backside of the light source device to the ambient via the heat sink.
In order to increase the dissipation area, the optical device in the form of a reflector may be arranged to connect to the remote phosphor element directly. Thus, heat generated by the phosphor element may be dissipated to the ambient via the outer surface of the reflector. Alternatively, the heat sink may be made larger in order to increase its heat dissipation efficiency. However, these solutions require modifications of the design for the LED module, the heat sink and/or the optical device. Also, when making the heat sink larger, the total size of the combination of the LED module and heat sink is increased, which counteracts the typical ambition to keep the construction small.
Thus, there is a need for a LED module with an improved heat removal without the above mentioned drawbacks.